Sulfonate functional polyvinyl acetals

Abstract

Polyvinyl acetals with low solution viscosities and maximum Newtonian flow behavior contain sulphonate-functional vinyl ether or sulphonate-functional allyl ether units in addition to conventional vinyl ester, vinyl alcohol, and vinyl acetal units.

The invention claimed is: 
     
       1. Sulphonate-functional polyvinyl acetals comprising from 0.1% to 50% by weight of residues derived from vinvloxyalkyl or allyloxyalkyl substituted sulfonic acid, selected from the group consisting of vinyloxyalkylsulphonates and allyloxyalkylsulphonates having unsubstituted or substituted, unbranched or branched C 1 -C 6 -alkyl groups, and mixtures of vinyloxyalkylsulfonates and allyloxyalkylsulphonates. 
     
     
       2. The sulphonate-functional polyvinyl acetals of  claim 1 , comprising:
 a) from 20% to 70% by weight of vinyl acetal units, 
 b) from 10% to 30% by weight of vinyl alcohol units, 
 c) from 0.5% to 20% by weight of vinyl- or allyloxyalkylsulphonate units or mixtures thereof, 
 d) from 1% to 10% by weight of vinyl ester units, the weight percentages are based on the total weight of the sulphonate-functional polyvinyl acetates. 
 
     
     
       3. A process for preparing a sulphonate-functional polyvinyl acetal of  claim 1 , comprising acetalizing a hydrolysed vinyl ester copolymer of one or more monomers comprising vinyl esters, unbranched or branched C 1-15  alkane carboxylic acids, sulphonate-functional vinyl ether and/or sulphonate-functional allyl ether comonomer(s), having ≧50 mol % of vinyl alcohol units, with one or more C 1-15  aliphatic aldehydes, C 6-15  aromatic aldehydes, or mixtures thereof. 
     
     
       4. The process of  claim 3 , wherein at least one aliphatic aldehyde selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde, is used for acetalizing. 
     
     
       5. In a printing ink containing at least one pigment and employing a polymer binder, the improvement comprising employing as at least one binder, a sulphonate-functional polyvinyl acetal of  claim 2 . 
     
     
       6. The printing ink composition of  claim 5 , comprising from 5 to 20% by weight of pigment, and from 5 to 15% by weight of sulphonate-functional polyvinyl acetal binder and solvent. 
     
     
       7. In a corrosion protection composition, an unfired ceramic composition, a metal powder composition, or can coating composition, where an organic binder is employed, the improvement comprising selecting as at least one binder, a sulphonate-functional polyvinyl acetal of  claim 1 . 
     
     
       8. A can coating composition of  claim 7 , further comprising a crosslinking agent. 
     
     
       9. The composition of  claim 8 , wherein said crosslinking agent comprises an epoxy resin.